In the biomedical field there are a number of procedures which involve treating specimens on microscope slides with various reagents. For example, in the fields of hematology, histology, cytology, microbiology and immunology various cultures, smears and organisms are placed on microscope slides and then treated with stains, counterstains, decolorizers, fixers, dehydrators, antigens, antibodies and washes to properly identify or differentiate the specimen under study.
Where these procedures are performed manually the various reagents are generally poured onto the slides and washed off, or the slides may be placed in racks and sequentially dipped in one reagent container after another. Each reagent is held in contact with a specimen a predetermined length of time and the racks are often placed in a rinse solution between treatment with the various reagents or dyes.
Dyes are normally very potent and messy to handle. Accordingly, dipping procedures, while simple, are lengthy and tedious considering the number of slides that may have to be prepared and the quality of the finished product can be affected by the procedure used, especially the freshness of a treatment solution.
Various devices have been proposed to mechanize or automate slide staining techniques. A very common approach is to provide an indexical slide rack which moves slides along a predetermined path dipping the slides into one container after another. Machines have also been constructed to transport individual slides along a processing platen where each slide is treated with various dyes and intermittent rinses. Another known device simply floods a slide chamber with dye and then causes the dye to be removed from the chamber before a new solution is introduced. These known devices generally are relatively large in dimension, and in many cases must discharge substantial amount of dye after only one cycle of use. In addition to other disadvantages, these devices and techniques can result in chemical and cellular cross contamination and interreaction with specimens on different slides unless care is taken in supplying and removing treating solution from the slides.